Crinoid (Sea Liles) with Pecten Bivalve, from Charmouth, England (No.108)

Crinoids, popularly known as sea lilies and feather stars, possess a massive calcite skeleton, and were so abundant in the Palaeozoic seas that their remains formed vast thicknesses of limestone. Most Crinoids are attached to sea bed by a flexible stem, circular or pentagonal in sections, and made up of numerous disc like plates called columnals. At the top of the stem is a swollen cup or calyx (head) to which the arms are attached. The arms are used to filter food from the water. Soon after death, the entire skeleton normally falls apart into the small, separate plates called ossicles. In contrast, well-preseved crinoids are rare and beautiful fossils.